This invention relates to a stereo reproduction system which can provide satisfactory localization effect in a broad listening area in a loudspeaker's small distance field.
Generally, in a two-channel stereo reproduction system most satisfactory localization effect (positional recognition of sound images produced by stereo reproduction) is obtainable at a listening position a certain distance forward from the position midway between two loudspeakers such as in a relation where two loudspeakers and listening position constitute apices of a regular triangle.
This is so because the localization effect of the sound image can be obtained from the sound pressure difference and sound arrival time difference between the two ears. If the distance of the listening position from the loudspeakers is large, the difference between the distances from the listener to the two loudspeakers itself does not greatly affect the sound pressure difference and time difference between the two ears. Therefore, satisfactory localization effect can be obtained in comparatively wide areas on both sides of a line vertically bisecting the line connecting the two loudspeakers (hereinafter referred to as center line). However, in a listening area where the distance of the listening position from the loudspeakers is small, the sound pressure difference and time difference between the two ears due to the difference between the distances, through which sounds from the two loudspeakers reach the listener, vary greatly depending on the listening position. Therefore, the listening area where satisfactory localization effect can be obtained is limited to a small area intersecting the center line between the two loudspeakers. Therefore, the smaller is the distance from the loudspeaker the narrower is the satisfactory listening area. The listening area where the satisfactory localization effect is obtainable can be shifted from the aforementioned small area intersecting the center line through electrical control of the sound pressure difference and time pressure difference of either one of the left and right channel signals with respect to the other. However, even if it can be shifted, it is impossible to expand the satisfactory listening area.